Carburetor



Oct. 29, 1968 B. WALKER 3,408,054

CARBURETOR Original Filed Aug. 16, 1965 2 Sheets-Sheet l IN l/Ef/W Oct. 29, 1968 a. WALKER 3,408,054

CARBURETOR Original Filed Aug. 16, 1965 2 Sheets-Sheet 2 United States Patent 3,408,054 CARBURETOR' Brooks Walker, 1280 Columbus Ave.,-.

San Francisco, Calif. 94133 Continuation of application Ser. No. 479,881, Aug. 16, 1965. This application July 26, 1967, Ser. No. 656,292

9 Claims. (Cl. 261- -39) ABSTRACT OF THE DISCLOSURE A carburetor having two fuel circuits from the float bowl. One circuit leads to the transfer port and the other circuit leads to the mixing chamber below the butterfly throttle valve. A flexible reed overlaps the transfer port and is engaged by the valve toregulate the opening of the transfer port. When the valve is in closed position the transfer port is closed and idle fuel mixture is admitted by the other circuit.

This application is a continuation of my application Ser. No. 479,881, filed Aug. 16, 1965, now abandoned.

This invention pertains to an improved carburetor for an engine with components to produce less unburned hydrocarbons in the exhaust and therefore produce less smog.

Most carburetors have an idle fuel circuit that leads from the float bowl up above the top of the fuel in the bowl past an air bleed that also serves as an antisyphon bleed down past a series of transfer ports or a transfer port slot that is passed over by the throttle disc in moving from the cracked idle position to the part open throttle position. Such construction is shown in Glenns Auto Repair Manual, 1962, page 234 and page 235.

This invention involves a separate idle fuel circuit leading from the float bowl to above the level of the fuel in the float bowl, past an adjustable air bleed (that could be a fixed orifice or replaceable orifice of varying size) down to the mixing tube for the air and fuel to idle on the engine side of the throttle butterfly.

With this invention the engine is idled with the throttle butterflies closed and most of the air to idle being mixed with the fuel to idle and preferably being delivered near the center of the throat leading from the throttle butterfly to the engine. Crankcase breathing air could enter on the engine side of the throttle plate if desired or be mixed with the air to idle as above.

Another feature is an improved carburetor in which the fuel to idle is not competing with the transfer port which is generally exposed to engine manifold suction as the throttle is opened from idle to part or full throttle, and open to the atmosphere or slight suction between the air cleaner and the throttle at idle conditions.

Another feature is a reed or vane that covers the transfer port above the throttle when the throttle is closed or near closed but moves away from the transfer port by manifold suction on the engine side of the throttle butterfly so that the transfer port is open on the engine side of the throttle butterfly but closed on the side of the butterfly away from the butterfly.

With this arrangement there are other advantages two fuel circuits from the float bowl-one to the transfer port and another to the mixing chamber for the air and fuel to idle. A separate port may admit crankcase breathing past a suction operated valve controlling a valve to a conventional small orifice at high suction and a larger port for lighter intake suction.

Another feature is the use of a sandwich below the usual carburetor with separate fuel line or lines for the idle fuel to feed through to the tube where the air and fuel to idle are mixed.

Patented Oct. 29, 1968 'Another feature is the means for choking the air to idle by means of the normal automatic choke mechanism for better starting and cold engine operation.

Another feature is the'provision of a visible tube for the fuel to idle between the air bleed and the chamber where the idle fueland air are mixed. This .aids in adjusting the carburetor and in research and studying the flow of rich fuel and air to the mixing area for the air and fuel to idle. v

' A means B for holding up the float when the idle fuel is shut off and auxiliary air bleed for deceleration could be used, as are shown in my US. application Ser. No. 444,572, dated Apr. 1, p 1965, entitled: Carburetor, andis now'Patent No. 3,336,012, issued Aug. 18, 1967.

Another feature is the provision of a suction gage in the line supplying this fuel to idle between the mixing chamber and the air bleed to the fuel to idle passage for better study of the fuel flow in the carburetor, etc.

Other features will be pointed out in the accompanying specifications and claims.

I have illustrated my invention in the accompanying drawings, in which:

FIG. 1 is a side elevation partly in section of a carburetor, part of an air cleaner and part of an engine showing one form of this invention.

FIG. 2 is a -view partly cut away of another form of fuel feed.

FIG. 3 is a view partly cut away of still another form of idle fuel feed.

In FIG. 1 I have shown a carburetor 10 having a main throat 11, a choke valve 12, mounted on a choke shaft 13. A throttle butterfly valve 14 is mounted on a throttle shaft 15. A float bowl 8 encloses a float 16 that operates a fuel feed needle valve 17 in the usual manner. Float 7 is pivoted by pin 7a.

Tube 18 leads from near the bottom of the float bowl 15 past air bleed port 19 down tube 21 to transfer port slot 22.

A reed 23 is supported by ring 24 and has action limiting guard 25 at its end, toward the flow to the engine. The throttle butterfly valve 14 presses this reed against the transfer port when the throttle is closed. If the throttle is opened the reed moves away from the transfer port below the throttle valve to allow fuel to flow to the engine from the engine side of the butterfly 14 due to the engine manifold suction acting to pull the reed away from the transfer port on the engine side of the throttle butterfly. Probably the reed will be sucked against the transfer port above the butterfly due to the suction on the port belov and no suction or approximate atmospheric pressure on the transfer port above the partially opened throttle valve 14.

A tube 31 leads from near the bottom of the float bowl to adjustable screw 32a which controls bleed air from air bleed 32 (which could be a replaceable orifice of different size for adjustment). An adjustable idle fuel flow valve 33 controls the flow of rich fuel and air to idle. Tube 35 may be transparent so that the flow of rich fuel and air to idle can be visualized to aid in adjustment of the carburetor or in studying the action of this part of the carburetor.

The suction gage 41 is connected to the tube 42 and port 43 which leads from the fixture 36 which is connected to tube 35. Fixture 35 is connected and leads to passage 37 past valve 38, passage 39 and 40 to mix with air to idle passing through tube 65, passage 66 to mixing tube 45, then out through port 46b.

Telescoping tube 46 is capped by 46:: and has port 46b and is operated by control rod 47 passing through adjustable air flow to idle valve 48. Control rod 47 can be operated by a diaphragm or solenoid to shut off the fuel and air to idle when decelerating above a predetermined speed as explained in my copending application Ser. No. 439,168, entitled Carburetor, filed Mar. 12, 1965. Rod 47 shuts olf the idle fuel and air by moving to the right as viewed in FIG. 1, while valve 50 in said application shuts off the idle fuel by moving to the right as viewed in FIG. 1, so the control will have to act accordingly.

This gage 41 reading when compared to the suction in the intake manifold gives a good indication of the action of the idle fuel in passage or tube 31.

A choke valve 61 is controlled by the action of choke shaft 13, by arm 13a, rod 62, and arm 61a. Choke shaft 13 may be controlled by thermal choke control 65 by rod 66. Thermal choke control 65 may be mounted on the exhaust manifold 67 or receive heat in any suitable manner.

By this system the fuel to idle flows from the float bowl through tube 31 past idle fuel valve 33. Air for the rich idle fuel and air enters past adjustable bleed 32 and adjustable valve stem 32a and the rich idle fuel and air flows through tube 35 (which may be transparent) through fitting 36, passage 37, past idle adjustment needle 38, passage 39, 40 to enter mixing chamber 45, and then enters the carburetor main throat 11a through port 46b of sliding tube 46. Sliding tube 46 can be controlled to shut off the idle fuel if that is desired as in said pending case, Ser. No. 439,168, entitled Carburetor.

Crankcase breathing could enter from the usual control valve (not shown) through tube 63 and past port 64 to the engine side of the throttle valve in passage 11a.

By this means I have provided an idle circuit that does not compete with the action of the transfer port and the fuel circuit that feeds the idle port so that better control of the idle fuel flow is obtained at all operating conditions and the transfer port is operated independently with the addition of the reed control of the transfer port if desirable. The float 16 can be held up during idle fuel shut off by diaphragm B, control rod B1 and spring 16a, if desired.

In FIGS. 2 and 3 I have shown alternate idle fuel pickup tubes and adjustments.

In FIG. 2 fuel to idle is picked up through tube 31a and the flow of fuel is adjusted by valve 70 before the idle air enters past valve 374 and before the rich fuel and air enter tube 35.

In FIG. 3 fuel to idle enters through tube 31b and is adjusted by valve 70 after the bleed air enters past valve 32a.

An orifice 31b may he used if desired to control the flow of fuel and create a better suction on the air bleed, particularly in the construction shown in FIG. 3.

I claim:

1. A carburetor comprising a body member having a tubular passageway therethrough, a butterfly throttle valve pivotally mounted in the passageway for movement between an open position for flow of fluid therethrough and a closed position for preventing fluid flow, a

transfer port in the wall of said passageway adjacent the periphery of said valve for admitting rich fuel thereinto, and means operable by the valve for adjusting the transfer port to effectively close the flow therethrough in the closed position of the valve and to increase the flow as the valve is moved toward the open position.

2. A carburetor as defined in claim 1 wherein said means comprises a flexible reed secured at one end to said wall and overlapping the transfer port.

3. A carburetor as defined in claim 2 further including a guard for limiting the movement of the other end of the reed away from the wall.

4. A carburetor as defined in claim 1 further including means for admitting an idle fuel mixture into the central zone of the passageway downstream of the valve.

5. A carburetor as defined in claim 1 further including means to generate and conduct an idle fuel mixture to the passageway, said generating means comprising duct means for conducting a rich fuel mixture into a mixing chamber, a conduit for conducting air into said chamber for mixing with the rich fuel mixture to form an idle fuel mixture, and a discharge conduit for conducting said idle fuel mixture into the central zone of the passageway downstream of the valve.

6. A carburetor as defined in claim 5 further including means in said air conducting conduit responsive to heat for controlling the flow of air therethrough.

7. A carburetor as defined in claim 1 further including means to admit an idle fuel mixture into said passageway downstream of the transfer port.

8. A carburetor comprising a body member having a tubular passageway therethrough, a transfer port in the wall of said passageway for admitting rich fuel thereinto, a throttle valve pivotally mounted in the passageway for movement between an open position for flow of fluid therethrough and a closed position for preventing fluid flow, a flexible reed secured at one end to said wall and overlapping the transfer port, and means mounting the throttle valve for engagement with said reed to regulate the distance of the reed from the transfer port as the throttle valve is pivoted in the closing range of movement.

9. A carburetor as defined in claim 8 wherein the transfer port overlaps the upstream edge of the throttle valve when said valve is in the closed position.

References Cited UNITED STATES PATENTS 1,178,296 4/1916 Cahill 261- 1,865,851 7/1932 Geiger 261-4l 2,327,592 8/1943 Chisholm 261-23 2,705,135 3/1955 Gehner 26l4l 2,877,998 3/ 1959 Cornelius.

3,151,604 10/1964 Walker et al. 26141 3,201,097 8/1965 Arndt 261--41 HARRY B. THORNTON, Primary Examiner.

TIM R. MILES, Assistant Examiner. 

